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WCRefreshEvent.h
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00001 //# WCRefreshEvent.h: class which stores WorldCanvas refresh event information
00002 //# Copyright (C) 1993,1994,1995,1996,1999,2000
00003 //# Associated Universities, Inc. Washington DC, USA.
00004 //# 
00005 //# This library is free software; you can redistribute it and/or modify it
00006 //# under the terms of the GNU Library General Public License as published by
00007 //# the Free Software Foundation; either version 2 of the License, or (at your
00008 //# option) any later version.
00009 //# 
00010 //# This library is distributed in the hope that it will be useful, but WITHOUT
00011 //# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
00012 //# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
00013 //# License for more details.
00014 //# 
00015 //# You should have received a copy of the GNU Library General Public License
00016 //# along with this library; if not, write to the Free Software Foundation,
00017 //# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
00018 //# 
00019 //# Correspondence concerning AIPS++ should be addressed as follows:
00020 //#        Internet email: aips2-request@nrao.edu.
00021 //#        Postal address: AIPS++ Project Office
00022 //#                        National Radio Astronomy Observatory
00023 //#                        520 Edgemont Road
00024 //#                        Charlottesville, VA 22903-2475 USA
00025 //# 
00026 //# $Id$
00027 
00028 #ifndef TRIALDISPLAY_WCREFRESHEVENT_H
00029 #define TRIALDISPLAY_WCREFRESHEVENT_H
00030 
00031 #include <casa/aips.h>
00032 #include <display/Display/DisplayEnums.h>
00033 #include <display/DisplayEvents/WorldCanvasEvent.h>
00034 
00035 namespace casa { //# NAMESPACE CASA - BEGIN
00036 
00037 class WorldCanvas;
00038 
00039 // <summary>
00040 // Class which stores WorldCanvas refresh event information.
00041 // </summary>
00042 
00043 // <use visibility=export>
00044 
00045 // <reviewed reviewer="" date="yyyy/mm/dd" tests="" demos="">
00046 // </reviewed>
00047 
00048 // <etymology>
00049 // "WCRefreshEvent" is a contraction and concatenation of "WorldCanvas",
00050 // "Refresh" and "Event", and describes refresh events occuring on 
00051 // WorldCanvases.
00052 // </etymology>
00053 
00054 // <prerequisite>
00055 // <li> <linkto class=WorldCanvasEvent>WorldCanvasEvent</linkto>
00056 // </prerequisite>
00057 
00058 // <synopsis> 
00059 // This class adds to the information stored in the <linkto
00060 // class=WorldCanvasEvent>WorldCanvasEvent</linkto> class.  It adds
00061 // information describing the reason a refresh event has occurred.  An
00062 // object of this class is generated and distributed to all registered
00063 // WCRefreshEvent handlers whenever a refresh is explicitly or
00064 // implicitly generated on a WorldCanvas.
00065 //
00066 // The reason field can be used to minimize the computation required
00067 // to redraw the screen, or it can be ignored, forcing all elements to
00068 // be redrawn.  The reason for the refresh can be one of the
00069 // following:
00070 //
00071 // <dd> Display::UserCommand 
00072 // <dt> The refresh event was caused by the user explicitly calling
00073 // the <linkto class=WorldCanvas>WorldCanvas</linkto> refresh
00074 // function.
00075 //
00076 // <dd> Display::ColorTableChange
00077 // <dt> The refresh event was caused by a change in the distribution
00078 // of colors on the <linkto class=PixelCanvas>PixelCanvas</linkto>.
00079 // Graphical elements that are dependent on colormaps need to be
00080 // re-drawn.  Cached display lists that include colormap-dependent
00081 // graphical elements must be rebuilt.
00082 //
00083 // <dd> Display::ColormapChange
00084 // <dt> This is a less severe version of the above refresh reason
00085 // (Display::ColorTableChange), and means that a single Colormap has
00086 // been modified, but that the overall distribution of colors remains
00087 // unchanged, ie. other Colormaps in this WorldCanvas' ColorTable are
00088 // unaffected. 
00089 //
00090 // <dd> Display::PixelCoordinateChange
00091 // <dt> The <linkto class=PixelCanvas>PixelCanvas</linkto> has changed
00092 // size.  Usually this means the graphics drawn must be translated to
00093 // a new position (recentered) which can be done by translating all
00094 // primitives and display lists.
00095 //
00096 // <dd> Display::LinearCoordinateChange
00097 // <dt> The linear coordinate system which is overlaid on the
00098 // PixelCanvas (normally by a <linkto
00099 // class=WorldCanvas>WorldCanvas</linkto> has changed.
00100 //
00101 // <dd> Display::WorldCoordinateChange
00102 // <dt> The world coordinate system which is overlaid on the 
00103 // PixelCanvas (normally by a <linkto
00104 // class=WorldCanvas>WorldCanvas</linkto> has changed.
00105 //
00106 // <dd> Display::BackCopiedToFront
00107 // <dt> The back buffer has been written to the screen.  Only
00108 // transient graphics drawers should be interested in this refresh
00109 // reason.  Any graphics which are required to be visible over
00110 // everything else on the PixelCanvas (or WorldCanvas) should catch 
00111 // and respond to this refresh reason.  Examples include interactively 
00112 // constructed regions, eg. a zooming box.
00113 // </synopsis>
00114 
00115 // <example>
00116 // </example>
00117 
00118 // <motivation> 
00119 // A compact way of passing refresh event information around the
00120 // display classes was needed, with a functional but tight and
00121 // efficient interface.
00122 // </motivation>
00123 
00124 // <thrown>
00125 // None.
00126 // </thrown>
00127 
00128 // <todo asof="1999/10/15">
00129 // None.
00130 // </todo>
00131 
00132 class WCRefreshEvent : public WorldCanvasEvent {
00133 
00134  public:
00135 
00136   // Constructor taking a pointer to the WorldCanvas for which the
00137   // event is valid, and the reason for the refresh.
00138   WCRefreshEvent(WorldCanvas *wc, const Display::RefreshReason &reason);
00139   
00140   // Destructor.
00141   virtual ~WCRefreshEvent();
00142 
00143   // Why did the refresh occur?
00144   virtual Display::RefreshReason reason() const 
00145     { return itsRefreshReason; }
00146 
00147  protected:
00148 
00149   // (Required) default constructor.
00150   WCRefreshEvent();
00151 
00152   // (Required) copy constructor.
00153   WCRefreshEvent(const WCRefreshEvent &other);
00154 
00155   // (Required) copy assignment.
00156   WCRefreshEvent &operator=(const WCRefreshEvent &other);
00157 
00158  private:
00159 
00160   // Store the reason for the refresh here at construction.
00161   Display::RefreshReason itsRefreshReason;
00162 
00163 };
00164 
00165 
00166 } //# NAMESPACE CASA - END
00167 
00168 #endif
00169 
00170